1. Field of the Invention
The present invention is related to a service retrieving method and a service retrieving apparatus for providing such information for a node which tries to receive a service, while this information indicates that which nodes provide which services in a network.
2. Description of the Related Art
While various sorts of services may be received via a network, even in the same sort of services, these services may contain certain services whose attributes such as qualities and communication protocols are different from each other, depending upon servers which may provide these services.
[Service Attribute]
For example, in the case that a user is connected via a network to a server so as to receive a print service, the following differences may exist, depending upon servers, namely, qualities such as resolution achieved in print-out operation; performance such as paper ejecting speeds; additionally-provided functions as to whether or not a sorter is equipped; communication protocols such as various sorts of print protocols; use permissions as to whether or not an access right is present; and expenses (will be referred to as “service attributes” hereinafter).
[Service Location (Service Position)]
Since a service may be identified based upon a network address, a domain name, and a URL (will be also referred to as a “service location (service position)” hereinafter) of a server apparatus which provides the service, a user can access the server apparatus for providing the service by using this service location from a client apparatus such as a scanner.
It should be understood in the below-mentioned descriptions that while an expression “server (apparatus)” and an expression “client (apparatus)” are described, the former implies such an apparatus for widely providing services and the latter implies such an apparatus for widely receiving services irrespective of actual names thereof.
In this case, as explained above, since services own attributes (service attributes), users are required to select a proper server by considering such a fact that which types of attributes of services may be received from any servers under which restriction conditions (protocols, charging methods and the like) and under which measuring bases (expenses etc.).
However, these users can hardly master such acknowledges. In particular, in the case that a user firstly accesses a network, and/or in such a case that while the user is separated from such a network to which this user usually accesses, this user temporarily accesses another network, the user normally has no such knowledge.
On the other hand, wide-area networks such as the Internet are constructed in such a manner that a plurality of networks are logically constituted in a hierarchical structure and these plural networks are mutually connected so as to form a collected member, while these plural networks correspond to IP subnets, enterprise intranets, Internet service providers, and the like. The above-explained respective networks are not made in an equal quality. That is, operation subjects of these networks are firstly different to each other, and many other aspects such as network designing methods and network operating methods are different from each other.
Networks contained in such a wide-area network are mutually connected to each other via relay apparatus such as routers and fire walls, while preventing occurrences of interference among these networks.
In order to retrieve a service location by considering a service attribute, for instance, there is such a service location extracting method. That is, while detecting attributes of services which are provided by all of nodes to which a user can reach in a network, such a service location which is desired by the user is extracted based upon the detected service attributes.
Such a service location retrieving method may be realized by, concretely speaking, a pre-registering system, a round-robin system, a multicast system, or a WWW robot retrieving system, and so on.
[Pre-Registering System]
In a pre-registering system, when a server which provides services is installed, while service locations, service attributes, and the like have been registered in a database equipped with a retrieve function, previously-registered information is retrieved, and the retrieved result is provided for a user.
As an example of this pre-registering system, there are described an enterprise organization directory using an LDAP (Lightweight Directory Access Protocol, Version 3; IETF PFC2251), and “Cleaning House” in XEROX corporation XNS “Summary of local area network, Ethernet” revised version-2, written by KAMIYA, published by MARUZEN K.K. on Mar. 25, 1988).
This pre-registering system requires such a database for managing service attributes and service locations of all of nodes in a network in a batch manner.
[Round-Robin System]
In a round-robin system, a client apparatus for retrieving services accesses all of network addresses contained in address spaces of a network so as to inquiry a service attribute.
As an example of this round-robin system, there is provided; Serial Pinging with employment of ICMP (Internet Control Message Protocol; IETF RFC792)•echo.
This round-robin system requires traffics and processing time in correspondence with a dimension of an address space.
[Multicast System]
In a multicast system, response requests to a server by way of a multicast communication (IP multicast etc.) are issued, and the server advertises own services by way of a multicast communication, or any one of these operations is carried out.
As an example of this multicast system, there are provided; an SLP (Service Location Protocol, Version 2; IETF RFC2608), and an SSDP (Simple Service Discovery Protocol).
In accordance with the multicast system, service attributes can be retrieved within a range over which multicast communications can be reached, the range over which multicast communications can be reached is restricted based upon routers/fire walls and existence time of packets (total HOP number of routers), and the like.
A range in which service attributes can be retrieved/acquired by this multicast system (will also be referred to as “service acquiring area”) is restricted by a position in a network space, but is not directly restricted by a geographic distance between a server apparatus and a client apparatus.
In view of operations, the service acquiring area by way of the multicast system may be predicted to be limited to, for example, such a range as networks whose management subjects are identical to each other. As a result, the following prediction may be established. That is, a large number of service acquiring areas which are isolated from each other are present in a wide-area network.
The multicast system requires both processing time and traffics in response to a dimension of a reachable range of the multicast communication.
[WWW Robot Retrieving System]
In a WWW robot retrieving system, while a program called as either a “retrieve engine” or a “retrieve robot” is employed, a hyper link established in WWW information providing services is automatically traced so as to find out another WWW information providing service, and this found WWW information providing service is registered in a database. For instance, a keyword retrieve by a text with respect to this database is provided with a user.
As an example of this WWW robot retrieving system, Lycos and Alta Vista etc. are proposed.
Operations of the retrieve robot employed in this WWW robot retrieving system may depend upon such a WWW system as an HTTP (Hyper Text Transfer Protocol, Version 1.0; IETF RFC1945) and a W3C HTML (Hyper Text Markup Language), and the retrieve robot can retrieve only services provided by a WWW server.
Also, in accordance with this WWW robot retrieving system, since the retrieve robot traces the hyper link, large traffics occur in the network, and aplenty of processing time is required so as to reflect the retrieved results on the database and update the contents of the database.
Also, in an actual case, as previously explained, only the network retrieve function provider can apply this WWW robot retrieving system to a wide-area network.
[Retrieve Operation Executed by Considering Geographical Position]
Generally speaking, to provide services via a network, there is no geographical limitation but also no geographical distance. Services which may be utilized by users are not restricted based upon locations where server apparatus are installed.
As a consequence, a user who receives a service via a network may originally select a proper server apparatus by considering a service attribute, a restriction condition, and a measurement base, while this user need not consider a location where the server apparatus is installed, and but also such a fact that this server apparatus is connected to which network.
However, for instance, in such a case that a user is required to receive a service result such as a print service as goods, this user should consider a geographical position of a server apparatus in order to receive this service.
In such a case, the service retrieving operation should be performed as to a service location which is located close to both the user and a client apparatus, or another service location which is located at a user-accessible place even when this place is geographically located far from the user.
In this case, the service retrieving operation should be carried out by considering both a distance with respect to a network, and further, a geographical distance.
Generally speaking, in this case, there is no direct relationship between a geographical distance and a distance within a network. Therefore, for example, although a server apparatus is located in the vicinity of a user, since this server apparatus is connected to another network different from a network of a client apparatus, there is such a possibility that this server apparatus cannot be found out by a service retrieving operation closed in one network.
As a consequence, even when such a server apparatus is searched which is geographically located close to a user, a service retrieving operation should be carried out over a plurality of networks.
[Problems Caused by Use Permission]
Furthermore, in the case that a service is retrieved via a plurality of networks, there is a problem which is caused by a use permission.
In general, a use permission for using a service is performed by uniformly permitting uses of services to all of users, or by permitting a use of a service only to a re-registered user, irrespective of such a fact as to whether or not a user fee is charged.
In the latter case, namely in the case that a pre-registering operation is required for a use permission, an identification is required when a service is used.
While identification methods are different from each other every server apparatus, access to server apparatus cannot be permitted without entering passwords and thus, service attributes of server apparatus cannot be acquired in view of a security aspect.
As a consequence, even when a user tries to access such a server apparatus which employs the latter method, this user cannot access this server apparatus unless the user previously acquires a password, or the like for identification purposes, and therefore, this user cannot know the service attribute of this server apparatus.
As a method for providing such information for a node which tries to receive a service, while this information indicates that any nodes provide which services in a wide-area network where a plurality of networks are mutually connected to each other, for instance, Japanese Laid-open Patent Application No. Hei-10-56451 (will be referred to as a “publication 1” hereinafter) discloses the method for retrieving all of the nodes in the all-exclusive manner with employment of the ARP (Address Resolution Protocol) table.
Also, Japanese Laid-open Patent Application No. Hei-11-167585 (will be referred to as a “publication 2” hereinafter) describes such a method for collecting the information related to the services in the periodic manner by way of the multicast system so as to manage the collected information.
Also, Japanese Laid-open Patent Application No. Hei-11-195048 (will be referred to as a “publication 3” hereinafter) opens the method for determining the range used to retrieve the node in response to the cost information.
However, when the above-explained methods disclosed in the publications 1 to 3 are applied to a plurality of networks, a plenty of processing time is necessarily required, and also, traffics occurred in the networks are excessively increased.